Electric welding machine



A ril 3, 1928. v l,665,@67

J, W. MEADOWCROFT ELECTRIC WELDING MACHINE Fled March '7, 192'? 6 Sheets-Sheet l 3 a I N VEN TOR.

Josamfimowcaorr A TTORNEY.

J. w. MEADOWCROFT ELECTRIC WELDING MACHINE Filed 7. 1 927 6 Sheets-Sheet a INVENTOR. Joss w MEADOWCROFT A TTORNE Y.

April 3, 1928. 1,665,067.

, J. w. MEADOWCROFT ELECTRIC WELDING MACHINE Filed 7. 1927 a sheets-sheet 4 Fla. 4-

INVENTOR. JOSEPH -MEADOWCROFT A TTORNE Y.

April 3, 1928.

J. W. MEADOWCROFT ELECTRIC WELDING MACHINE s sheets-sheet 5 Filed March '7, 1927 INVENTOR.

JOSEPH 'MEADOWCROFT By M ATTORNEY.

Patented Apr. 3, 1928. v

UNITED STATES 1,665,067 PATENT OFFICE.

JOSEPH W. HEADOWCBOFT, OF PHILADELPHIA, PENNSYLVANIA, ABSIGNOB TO ED- WARD G. BUDD MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA,

A CORPORATION OF PENNSYLVANIA.

v ELECTRIC WELDING MACHINE.

Application filed larch 7, 1927. Serial No. 178,329.

-This invention relates to electric welding machines and more particularly to machines for electrically spot welding together sheet metal panels and other such structural parts.

In the manufacture of all metal automobile bodies, especially, it has been found advisable, both in the interests of increasing the speed of production as well as the economy of manufacture, to assemble the various sheet metal panels and stampings which make up the complete bodyby electrically welding them together. The method of welding most generally employed is spot welding wherein the panels or structural arts to be welded together are compressed iietween electrodes of comparatively small contact area and a current of electricit is passed through the electrodes. Difiicu ties ave been encountered i om time to time,

however, in spot welding the parts together, due to the fact that a number of the joints to be welded are often inaccessible-to the ordinary spot welding machine. Also it is often impractical to shift the work around the machine so as to bring the joint which is to be welded into proper position with respect to the welding electrodes.

It is among the special and principal objccts of this invention to provide an electric spot welding mechanism which is designed to permit the formation of spot welds in places which have been hitherto considered inaccessible for this type of weld.

Still another object of the invention is the provision of a spot welding machine which may be employed to efiect spotwelds irres ective of the position or the location of tie joint to be welded.

A still further object of the invention is 40 the provision of a spot welding machine which may be adjusted with respect to the work to be welded, this adjustment being characterized by the shifting of theweld ing axis from one' position to another as may be desired. In urtherance of this last mentioned object, the machine is so designed that it is capable of. a substantially universal adjustment with respect to the work to be welded.

A still further object of the invention is the provision of a spot welding machine. which is as compact and rugged in construction as itis efiicient and simple in operation.

A still further object of the invention is to provide a spot welding machine which is not only adjustable for various angular positions but which is also portable, thus greatly increasing the facility and ease with which the machine may be handled for effecting those weldswhich have been heretofore considered difiicult, if not altogether impossible.

Other objects of the invention will appear more 'fully hereinafter.

The invention consists substantially of a construction, combination, location and relative arrangement of parts, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally pointed outin the appended claims.

In the accompan in drawings- Figure 1 is a sid e e ovation of the complete machine;

Figure 2 is a cross sectional view of the central portion of themachine taken at right angles to Figure 1;'

Figure 3 is a cross sectional view taken on line 3-3 of Figure 1;

Figure 4 is a front elevation of the machine, the actuating arm of the machine bemg omitted in this figure;

Figure 5 is an enlarged View showing a portion of one of the outer plates and a brake mechanism associated therewith;

Figure 6 is a view similar to Figure 2 but showing the entire machine; and

Figure 7 is an enlarged view in cross section, taken on the line 7-7 of Figure 3.

The same part is designated by the same reference numeral wherever it occurs throughout the several views.

Referring more particularly to the drawings, it will be seen that the welding machine essentially consists of a transformer indicated generally by the reference numeral 10, a controlling rheostat 11, and a pair of electrode supporting arms 12 and 13, the

arm 13 being arranged for movement toward and away from the relatively stationar arm 12. An actuating arm 14' is operative y associated with the relatively movable electrode supporting arm 13in the manner described more fully hereinafter, this actuating arm bein provided with the usual switch, mechanism designated generally b the reference numeral A for opening an closing the primary circuit of the trans: former 10.

As shown in Figures 3 and 1, the welding lltl till

apparatus is provided with a pair of supporting brackets and 16 each of substantially inverted L shape, and the upper horizontally extending portions 17 and 18 there of being turned upwardly at their free ends as at 19 and 20, respectively, These upturned portions 19 and 20 of the supporting brackets embrace the opposite faces of an intermediately disposed member 21 and are secured thereto by means of a plurality of bolts 22, thearrangement being such that When the brackets 15 and 16 are joined together through the member 21 there is provided in effect a supporting yoke for the welding mechanism proper which is substantially in the shape of an inverted U. This is most clearly shown in Figures 3 and 4.

The member 21 is provided With a vertically extending bore 23, through which ex- J'rends the stem 24 of a supporting member This supporting member 25 is suitably formed at its upper end for engagement over a hook; or other such supporting device the referred form being that of an eye such as indicated by the reference numeral 26. The member 25 is further provided with a vertically extending bore 27 extending through out the entire. length of the stem 24 and communicating with the central opening in the eye 26-. The U shaped supporting yoke comprising the brackets 15 and 16 and the member 2i is rotatably supported upon thestem 24 of the supporting member 25 by means of a plurality of ball bearing races 28'suitably embracing the ball bearings 29 these ball bearing races 28 bein slipped over that portion of the stem 2 lviliich projects through the bottom, of the member 21. Nuts 30 are threaded upon the lower end of the stem 24k, thesenuts constituting the bottom abutment for the ball bearing" races 28. "these nuts further coo crate with an enlarged shoulder 31 "on tie supporting member 25 for preventing any relative vertical movement between the shaped supporting yolre and its su porting member 25 Without, however inter ering with any relative rotation therebetvvecnl Mounted within suitable apertures in the lower ends of the amns l5 13 of the supporting yohe are a pair oi inwardly ing stub shafts 32. and 33 respectively. lin

each instance the opposite ends of the stub elicits 32 and 33- are substantially reduced in cross section, so as to provide enlarged central portions 34: and 35, 'respectii'i'ely. forming outer inner annular shoulders. outer ends of the stub shafts are of substantially circular cross section and have thereto bearing races 36 which ar ear ranged to rotate fr ely within the co'opereating bearing races located within the apertures in the lower ends of the arms 1L5 lb of the supporting yolren Ball menses? ings 38 suitably disposed between the bearing races 36 and 37 assure free rotation of the stub shafts upon the yoke arms. Fixed to the inner ends of the stub shafts 32 and 33 and seated against the inner shoulders formed by the enlarged central portions 34 and tthereof are a. pair of circular plates 39 and 40. Nuts 41 and 42 are threaded upon the inner ends of the stub shafts against against the inner faces of the plates 39 and for effectually precluding any lateral displacement of the plates from their supporting shafts. The enlarged central portions 3i and 35 of the stub shafts are of sufficient thickness to provide substantial clearances between the plates 39 and 4-0 and the yoke arms 15 and 16, respectively.

Rotatably mounted in the supp'ortinq yoke arm, 15 immediately above the stub shaft 32 is an inwardly extending pinion l3 operable by the handle i l; This pinion 4-3 is geared to the stub shaft 32, the enlarged central ortion 34 of the latter being provided with teeth 45 for this purpose. Plates 39 and 40, being interconnected by a plurality of transversely extending strap members 46, it will thus be seen that upon operating the handle all a rotative movement will be imparted to the plates 39 and 40 as a unit.

The straps 46 which interconnect the plates 39 and 40 are in turn tied together by a plurality of intermediately disposed straps 47 arranged at right angles thereto. These straps 4-7 are arranged in pairs lying in spaced parallel planes at right. angles to the plates 39- and 40'. Supported between these pairs of strap members 47 is the transformer 10 from which depend the secondary leads 48- and d9. Secured to the outer faces of the front pair of strap members 47 by means of the bolts 50 are a pair of substantially channel shaped members 51; the base Walls 52 of which are spaced. forwardly from the respective strap members i? to which the members 51 are secured li'nterconnecting the forward pair of strap members 4-? at a point immediately above the upper ends of the channel members 51". is a transversely extending member 132i and seltltl llll cured to the extreme upper ends of these E a same strap members t? are a pair of angle members 33, the freely extending branches lift of which extend forwardly and down vvardly to support the controlling rheostat indicated generally by the reference nomerallh Secured to. the outer faces of the base Walls of the channel members M is an plate 55 upon which is detachebly secured by'rneans of the bolts 56 an annular collar for maintaining in position.

' bifu cated bearing member 53 in which ed the arena: arm 59. This cranlr is in turn connected to the forward end oft: short rod or stern 83 by means. cl

lit

" link 61 and the actuating arm 14, upon mounted the switch mechanism 15, ed to the crank arm shaft such that 1 actuation of the arm 14 the crank arm ay be rocked an amount suflicient to the stem i'orwardlythat is, in a time away from the forward end of the isi'ormer 10.

is most clearly shown in Figure 2, it a .7 be seen that the movable electrode supporting arm 13 has its upper end keyed, as at 61, to a shaft 62 rotatably supported in bearing bosses provided on the plates 39 and ill Fixed to the upper end of this electrode supporting arm 18 is a member indicated renerally by the reference numeral 63, this latter member being provided with a forwardly extending looped portion 64 to the upper surface of which is secured a substantially l. shaped member .65. The longer branch oi this L shaped member 65 extends vertically above the forwardly extending portion ofthemember andis provided with an opening in its upper end through which is projected the rod or stem 60. This rod or stem 60 is provided with an enlarged head its rear end, constituting the rear abutment for the compression spring 68 w ich surrounds that portion of the stem 60 extending rearwardly of the arm 66 of the member 65. The L shaped member 65 and.

the member 63 to which the shorter arm till thereof is secured jointly constitute what is in eli'ect a bell crank interconnecting the rod :1 60 and the electrode supporting arm ch is keyed to the shaft 62. By this arrangement, it will be seen that upon actuot the main actuating arm 14-, the rod or stem 60 will be drawn forwardly an extent sui cient to overcome the compressive force of the spring 68, with the result that the arm 66 of the bell crank member 65 will be actuated to impart a partial rotation to the shaft to which is secured the electrode supporting arm 13.

in order to maintain the electrode supporting arms 12 and 13 in normally separated position, there are provided a pair of spaced tension springs 69, the upper and lower ends of? which are respectively secured to brackets 70 carried by one of the transversely extending straps 46 and to forwardly extending arms 71 carried by the shaft 62 to which the electrode supporting arm 13 is :tor supplying current to the primary circuit of the transformer 10. The inner ends of the members 73 and 74 are externally threaded, as at 77 and 78, respectively, and have secured thereto by means of the nuts 79 and 80 a pair of terminal members 81 and 82, respectively. Suitable brushes 83, referably spring pressed, contact with the circumferential surfaces of the enlarged heads of the conductor elements 73 and 74, respectively, as the latter rotate with the stub shaft 32 when the handle 44 is operated. The leads for supplying current to the brushes 83 from the source of supply pass through the vertically extending bore provided for this purpose in the supporting member 25, the primary circuit of the transformer being completed by leads running from the terminal members 81 and 82 to the transformer primary terminals, respectively. The current conducting elements 73, 74, 81 and 82 are suitably insulated from each other, and from the stub shaft in which they are mounted, in a manner well understood in the art, the insulation for this purpose being clearly shown in Figure 7. Similarly, the electrode supporting arm 13 is insulated from its supporting shaft 62 and the actuating mechanism therefor, as is most clearly illustrated in Figure 2.

Each of the electrode supporting arms 12 and 13 are provided at the lower ends with suitable electrodes 85 and 86, respectively, to which welding current is supplied from the secondary circuit of the transformer 10 through the depending terminals 48 and 49, the latter of which is connected to the electrode supporting arm 13 by the flexible connection 87.

In order to protect the electrodes 85 and 86 against the excessive heat which is developed during the course of, the welding operations, there has been provided a system for circulating a cooling fluid through these electrodes. This system essentially consists of water or other cooling 'fluid tubes arranged to circulate the cooling fluid continuously and serially through the-welding electrodes. The connection 88, leading from the water supply,,continues to a two-way fitting 89 extending downwardly through the hollow stem the circulating fluid passing through one of the passages in this fitting to the connection 90 which follows closely the inside face of the yoke arm 16, thence passing outwardly through an opening 91 in said arm for connection with a second two-way fitting 92 which extends transversely through the horizontal bore 98 of the stub shaft 33. The circulating fluid passes through one of the passage ways in this two-way fitting 93 and continues through the flexible connection 94 to and through the electrode 86, from whence it passes through the connection 95 into and through the second electrode 85, finally passbrake shoe 100, substantiall ing through the return connection at) to the return passage of the two-way fitting 93, From this point, the circulating fluid coinpletes its return through the connection 97, the return passage in the fitting 89 and the flexible connection 98. The flexible connection 95, which directly interconnects the electrodes 85 and 86, is supported out of the way of these welding electrodes by a clip 99, which is suitably secured upon the inner face of the plate 40 adjacent the periphera edge thereof.

From the foregoing description, it will ap pear that a welding apparatus has been devised, which is capable of substantial (universal) adjustment with respect to the work to be Welded. The welding machine proper, comprising the transformer 10, the welding arms, and the actuating mechanism for moving these arms to effect the desired spot welds, may be rotated about a substantially horizontal axis by manually operating the handle 44, while the pivotal arrangement between the supporting'meinbcr 25 and the top of the supporting yolrc ot the machine pro or permits movement of the latter about a su stantially vertical axis. in order, however, to assure the maintenance of the weld ing machine in any desires fixed position with respect to its horizon axis; that is, in order to insure a detiuit angular relation between the welding a" and the horizontal, there has been pro ,ed a brake mechanism such as is best shown in Fig ure 5.

This mechanism essential 'y consists of a :nnbracing the enlarged central portion oi the stub shaft 33, the ends 101 and 102 of the shoe termi nating short of one another, and the end 102 being secured in any desired manner against rotation. A brake lining 103 may or may not be employed between the internal surface of the brake shoe 100 and the cireum ferential surface of the stub shaft 32 which it embraces. Secured to the inner surface of the plate 40 are a pair of spaced brackets 104 and 105the latter c dish constitute; the bearing for a stub s: t 106 journarcd therein. Fixed to this shaft 100 is the bell crank lever 10?, ti nger arm of which constitutes the lo, and the shorter arm of which h 31 otally con nected to its free end one o of a linla 10 5, The opposite end of th r 108 is in turn pivotally connected, 00, to a second link 110, this last merit" nl: being provided with an off-set port in. 111 having its free end pivotally eon as at 112, to a longitudinal'extension U1 e bracket 104;, A short link 113 is pi ct connected. at 114, to the oil-set p l the link .110, and is provided i x l outwardly projectin I through the elongated.

D a l J. l n

means? the plate 40 opposite the free end of the brake shoe 100. The boss 115 is secured in any desired manner to this free end of the brake shoe. A tension spring 117 has its opposite ends secured respectively to the shaft 106 and to the link 110, thus constantly urging the latter toward the shaft with the result that the brake shoe 100 embraces tightly the stub shaft 33. In order to release the brake shoe from its engagement with the stub shaft 33, it is only necessary to depress or partially rotate the bell crank arm 10? upon its shaft 106 to force the link 110 against the action of the tension spring 117, with the result that the short link 1113 produces an expansion of the brake shoe 100 to an extent suiiicient to permit the free rotation of the Welding machine proper by means of the operating handle 44:. Upon releasing the brake arm 107, the brake shoe automatically T008118 by virtue of the action of the spring 11? to prevent any further rotation.

It is, of course, to be understood that the foregoing description has been primarily for the purpose of explaining the preferred principles and mode of operation of the new welding apparatus, that considerable variations and changes may be made in the invention without departing from the spirit thereof as defined broadly and specifically in the appended. claims.

What is claimed as new and useful is:

1. Anelectric welding apparatus comprising a pair of interconnected plate members, a transformer supported between said menu bore. a pair of relatively movable electrode supporting arms connected to said transformer and extending beyond the peripheral edges of said plat-es, means for rotatably supporting said plates, transformer and. arms as a unit, and means for imparting a rotative movement to said unit.

2. An electric welding apparatus including a unit comprising a pair of laterally 3. An electric welding apparatus including a unit comprising a pair of interconnected side members, a transformer disposed between said members, a shaft rotatably supported by said members, an electrode sup ortine, arm electrically connected and rola- L y v tively tionary with respect to said tran former, a second electrode supporting arm electrically connected to said transformer,

said l. ter arm. being carried by said rot it able t, tor oscillating said to bring said arms into working relation, and means tending normally to maintain said arms in inoperative position.

4. In an electric welding apparatus, in combination, an overhead support provided with depending arms, a stub shaft rotatably mounted in each arm of said support, a plate fixed to each shaft, said plates being each spaced from the inner surfaces of said depending arms and being interconnected for rotation together, means associated with one of said shafts for imparting a rotative movement to said plates, and means associated with the other of said shafts for preventing unintentional rotation of said plates.

5. In an electric welding apparatus, in combination, an overhead support provided with depending arms, a welding unit carried by said arms, a handle rotatably mounted in one of said arms and operatively associated with said unit for imparting a rotative movement thereto, and means operatively associated with the other of said arms and with said unit for maintaining the latter in adjusted position.

6. In an electric spot weldin apparatus, a pair of spaced, interconnects plate members, horizontally aligned shafts upon which said members are respectively mounted,

mg said members, a transformer disposed between said members and carried by said straps, a transversely extending shaft rotatably supported between said members, an

electrode supporting arm fixed to said shaft and electrically connected to the secondary of said transformer, means for imparting a rotative movement to said-plate members, and means for oscillating said shaft independently of the rotation of said plate memers.

In testimony whereof I hereunto aflix my signature.

JOSEPH W.IMEADOWCROFT, 

